If you have been feeding the hogs through the winter, I’m worried that if you suddenly stop there isn’t much wild food around at this time of year. Are there definitely some hogs still around, there? Do you know what time the hogs arrive for the food – i.e. do you have a camera? Is there any chance that you could ‘supervise’ at least some feeding time, so that if there are still any hogs around, they get a chance of some food.
I realise that leaving out food all night probably isn’t going to work, as the rat will probably eat it, but I have found here – mostly with cats eating the food – that the hogs tend to turn up earlier if they have found the bowls empty, so you may be able to have an earlier supervised feed. I have found, in the past, that rats are more sensitive to noise, movement etc. than the hogs are, so that it’s often possible to scare them away without scaring the hogs.
Make sure that the hogs always have access to water, even if you aren’t feeding.